Name: ex vivo live imaging of lung metastasis and their microenvironment
Uploaded: 2016-02-03T14:00:00
Description: Watch this Scientific Journal Video about Ex vivo Live Imaging of Lung Metastasis and Their Microenvironment at JoVE.com

We thank Nguyen H. Nguyen for her technical help and Audrey O&#8217;Neill for support with the Zeiss Cell Observer spinning-disk confocal microscope. This work was supported by a Department of Defense postdoctoral fellowship (W81XWH-11-01-0139) and the Weizmann Institute of Science-National Postdoctoral Award Program for Advancing Women in Science (to V.P.).

All procedures described must be performed in accordance with guidelines and regulations for the use of vertebrate animals, including prior approval by the local Institutional Animal Care and Use Committee (IACUC).
1. Generation of Lung Metastases for Ex vivo Live Imaging (Transgenic or Tail Vein Injection)
NOTE: Lung metastases can be generated by utilizing genetically engineered mouse models or by intravenous (i.v) injection of cancer cells.
<o...

<ol>
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This manuscript describes a detailed method for ex vivo live imaging of lung metastasis in mouse models of metastasis. This imaging protocol provides a direct visualization of the dynamic and spatial tumor cell-stroma interactions within the lung microenvironment. It is a relatively easy and fast method that allows reliable imaging of lung metastasis for at least 4 hr. Movies acquired from these experiments can be used to track dynamic processes as cell motility and cellular interactions.
<p class="jove_cont...

The deadliest aspect of cancer is metastasis, which accounts for more than 90% of cancer-related morbidity and mortality1. Metastasis is a multistep process and due to its complexity, the exact cellular and molecular mechanisms that govern metastatic dissemination and growth are still elusive. To metastasize, tumor cells in the primary tumor must detach from their neighboring cells and basement membrane, cross through the extracellular matrix, intravasate, travel via blood or lymphatic vessels, extravasate at the secondary site, and finally, survive and establish secondary tumors. In addition to the properties of the tumor cells, the contribution from the microenvironment, which includes the adjacent stroma along with the normal counterparts of the cancer cells, is crucial for the seeding and establishment of metastatic lesions2.
Traditional methods to study metastatic seeding and growth examine static states, as tissues are excised and sectioned for histology. These data only generate a snapshot of this highly dynamic process. Although some useful information can be gained from these studies, the complicated process by which tumor and stromal cells interact during metastatic formation cannot be adequately assessed by these methods. Furthermore, it is not possible to gain insights into tumor or stromal cell migration patterns, which are important in establishing a colony at the distant site. In order to effectively study the metastatic process, it is essential to visualize various interactions between cancer cells and their microenvironment in a continuous manner and at real time. 
The lung is a common site for metastases from solid tumors as breast, colorectal, pancreatic cancer, melanoma and sarcoma3. Intravital imaging was previously used to study cell-cell interaction in various primary tumor and metastatic models4,5. Methods of lung imaging in mice, including intravital imaging, lung section imaging, and an ex vivo pulmonary metastasis assay have been published6&#8211;9. Intravital imaging of mouse lungs utilizes a thoracic suction window to stabilize the lungs6. This method is used for time-lapse imaging of the lung microcirculation and alveolar spaces. The anatomical location of the lungs poses a challenge to intravital imaging. In order to access the lungs, the chest cavity must be opened which leads to loss of negative pressure and collapsed lungs. This method only allows the visualization of a small part of the lungs and is technically demanding; an unnecessary complication in studies that examine processes that are independent of blood flow. Moreover, this method also requires gating out movement caused by breathing. This is done either by collecting images between breaths or during post image acquisition analyses10. The alternative ex vivo lung section imaging provides stability and depth, and also prepares lung parenchyma for immunostaining7. However, the lengthy sectioning process leads to an extensive delay between the time of animal sacrifice and the start of the imaging session. Moreover, the process of sectioning a mouse lung causes considerable amount of cell death8, thus interfering with the quality and quantity of imaging samples and perhaps needlessly altering tumor-stroma interactions. In order to technically bridge between the methods of intravital imaging and lung section imaging, while exploiting the advantages of the two techniques, a relatively fast and easy method for ex vivo lung imaging was developed. This method was achieved by imaging of non-sectioned whole lung lobes. Using this method, the motility of cancer cells as well as interactions between cancer cells and stromal cells in their microenvironment can be visualized in real time for several hours.

<table>
	<tbody>
		<tr>
			<td>MMTV-PyMT/FVB mice</td>
			<td>Jackson Laboratory</td>
			<td>2374</td>
			<td>Female mice</td>
		</tr>
		<tr>
			<td>ACTB-ECFP/FVB mice</td>
			<td>UCSF Werb lab</td>
			<td></td>
			<td>Female mice</td>
		</tr>
		<tr>
			<td>c-fms-EGFP/FVB mice</td>
			<td>UCSF Werb lab</td>
			<td></td>
			<td>Female mice</td>
		</tr>
		<tr>
			<td>FVB mice</td>
			<td>Jackson Laboratory</td>
			<td>1800</td>
			<td>Female mice</td>
		</tr>
		<tr>
			<td>GFP+ VO-PyMT cells</td>
			<td>UCSF Werb lab</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>70,000 kDa Dextran, rhodamine-conjugated</td>
			<td>Invitrogen</td>
			<td>D1818</td>
			<td>Dilute to&#160; 4mg/ml in 1 x PBS and store at -20&#160; &#176;C. Use 0.4 mg per animal.&#160;</td>
		</tr>
		<tr>
			<td>10,000 kDa Dextran, Alexa Fluor 647 conjugated</td>
			<td>Invitrogen</td>
			<td>D22914</td>
			<td>Dilute to&#160; 4mg/ml in 1 x PBS and store at -20&#160; &#176;C. Use 0.4 mg per animal.&#160;</td>
		</tr>
		<tr>
			<td>Anti-mouse Gr-1 antibody Alexa Fluor 647</td>
			<td>UCSF Monoclonal antibody core</td>
			<td></td>
			<td>Stock 1mg/ml. Use 7 ug per animal.</td>
		</tr>
		<tr>
			<td>Anesthetic</td>
			<td></td>
			<td></td>
			<td>Anesthesia approved by IACUC, used for anesthesia and/or euthanesia</td>
		</tr>
		<tr>
			<td>1X PBS</td>
			<td>UCSF cell culture facility</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS, USP sterile&#160;</td>
			<td>Amresco INC</td>
			<td>K813-500ML</td>
			<td>Ultra pure grade for i.v. injection</td>
		</tr>
		<tr>
			<td>Styrofoam platform</td>
			<td></td>
			<td></td>
			<td>Will be used as dissection board</td>
		</tr>
		<tr>
			<td>Fine scissors sharp&#160;</td>
			<td>Fine Science Tools</td>
			<td>14060-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Roboz Surgical Store</td>
			<td>RS-5135</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot bead sterilizer</td>
			<td>Fine Science Tools</td>
			<td>18000-45</td>
			<td>Turn ON 30min before use</td>
		</tr>
		<tr>
			<td>Air</td>
			<td>UCSF</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen</td>
			<td>UCSF</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Carbon dioxide</td>
			<td>UCSF</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL syringe without needle&#160;</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr>
			<td>27 G x 1/2 needle&#160;&#160;</td>
			<td>BD</td>
			<td>305109</td>
			<td>for i.v. injection</td>
		</tr>
		<tr>
			<td>20 G x 1 needle, short bevel&#160;&#160;</td>
			<td>BD</td>
			<td>305178</td>
			<td></td>
		</tr>
		<tr>
			<td>Low-melting-temperature agarose&#160;</td>
			<td>Lonza</td>
			<td>50111</td>
			<td>To make 10 ml of solution, weigh 0.2 g of agarose, add to 10 ml 1 x PBS, and heat to dissolve. Agarose will solidify at room temperature, so maintain in a 37 &#176;C water bath until used for inflation.</td>
		</tr>
		<tr>
			<td>RPMI-1640 medium without phenol red</td>
			<td>Life Technologies</td>
			<td>11835-030</td>
			<td></td>
		</tr>
		<tr>
			<td>24 well Imaging plate&#160;</td>
			<td>E&#38;K scientific</td>
			<td>EK-42892</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass cover slides, 15 mm&#160;</td>
			<td>Fisher Scientific</td>
			<td>22-031-144</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital CO2 and temperature controller</td>
			<td>Okolab</td>
			<td>DGTCO2BX</td>
			<td>http://www.oko-lab.com</td>
		</tr>
		<tr>
			<td>Climate chamber</td>
			<td>Okolab</td>
			<td></td>
			<td>http://www.oko-lab.com</td>
		</tr>
		<tr>
			<td>Cell Observer spinning disk confocal microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zen software</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted microscope</td>
			<td>Carl Zeiss Inc</td>
			<td>Zeiss Axiovert 200M</td>
			<td></td>
		</tr>
		<tr>
			<td>ICCD camera</td>
			<td>Stanford Photonics</td>
			<td>XR-Mega-10EX S-30</td>
			<td></td>
		</tr>
		<tr>
			<td>Spinning disk confocal scan-head</td>
			<td>Yokogawa Corporation</td>
			<td>CSU-10b</td>
			<td></td>
		</tr>
		<tr>
			<td>Imaris</td>
			<td>Bitplane</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>mManager</td>
			<td>Vale lab, UCSF</td>
			<td></td>
			<td>Open-source software</td>
		</tr>
	</tbody>
</table>

ex vivo live imaging of lung metastasis and their microenvironment

Metastasis is a major cause for cancer-related morbidity and mortality. Metastasis is a multistep process and due to its complexity, the exact cellular and molecular processes that govern metastatic dissemination and growth are still elusive. Live imaging allows visualization of the dynamic and spatial interactions of cells and their microenvironment. Solid tumors commonly metastasize to the lungs. However, the anatomical location of the lungs poses a challenge to intravital imaging. This protocol provides a relatively simple and quick method for ex vivo live imaging of the dynamic interactions between tumor cells and their surrounding stroma within lung metastasis. Using this method, the motility of cancer cells as well as interactions between cancer cells and stromal cells in their microenvironment can be visualized in real time for several hours. By using transgenic fluorescent reporter mice, a fluorescent cell line, injectable fluorescently labeled molecules and/or antibodies, multiple components of the lung microenvironment can be visualized, such as blood vessels and immune cells. To image the different cell types, a spinning disk confocal microscope that allows long-term continuous imaging with rapid, four-color image acquisition has been used. Time-lapse movies compiled from images collected over multiple positions and focal planes show interactions between live metastatic and immune cells for at least 4 hr. This technique can be further used to test chemotherapy or targeted therapy. Moreover, this method could be adapted for the study of other lung-related pathologies that may affect the lung microenvironment.

Using spinning-disk confocal microscopy, various mouse model systems and injectables, the metastatic microenvironment can be visualized and tracked over time. Using an MMTV-PyMT; ACTB-ECFP; c-fms-EGFP triple transgenic mouse model, different cellular components are fluorescently labeled (Figure 2A, Movie 1). The typical structure of the lung parenchyma can be visualized in the CFP channel since all cells express ECFP under the &#946;-actin promoter. Larger/multicellular lung met...

Watch this Scientific Journal Video about Ex vivo Live Imaging of Lung Metastasis and Their Microenvironment at JoVE.com

Ex vivo Live Imaging of Lung Metastasis and Their Microenvironment

We describe a relatively simple method for ex vivo live imaging of the tumor cell-stroma interactions within lung metastasis, utilizing fluorescent reporters in mice. Using spinning-disk confocal microscopy, this technique enables visualization of live cells for at least 4 hr and could be adapted to study other inflammatory lung conditions.

Ex vivo Live Imaging of Lung Metastasis and Their Microenvironment

Metastasis is a major cause for cancer-related morbidity and mortality. Metastasis is a multistep process and due to its complexity, the exact cellular ...

The overall goal of this procedure is to visualize dynamic tumor cell stroma interactions within lung metastases.This method can help answer key questions in the cancer metastasis field, such as how are metastasis established.and what cell types within the micro-environment are involved in this process?The main advantage that this technique offers is that this is a fast and easy method for ex vivo lung imaging that enables visualization of live cells for at least four hours.This technique may have furthered our understanding of mechanisms of action of various targeted therapeutics for treatment of lung metastasis.We first had an idea for this method when we were examining metastasis by lung section imaging and were struggling with extensive cell death as a result of this procedure.To prepare the lungs for ex vivo live imaging, begin by immobilizing the mouse on a polystyrene foam lid covered with a piece of soaker and sterilize the animal with 70%ethanol.Next, using surgical scissors make a transverse epigastric incision through the skin, followed by a similar incision through the peritoneum.Then, moving the dissection board into a vertical position, cut the descending aorta, so that the blood pools into the abdomen and not into the chest cavity.Snip the small opening in the diaphragm to release the vacuum.Then, cut along the rib cage to excise the diaphragm and to visualize the lungs.Using surgical scissors, cut the skin up to the trachea over the rib cage leaving the ribs intact.Then, separate the skin from the rib cage, and remove the surrounding connective tissue to expose the trachea, taking care not to damage the trachea itself.Snip a small opening approximately one millimeter in diameter in the exposed trachea, parallel to the cartilaginous rings as close to the larynx as possible without cutting completely through the trachea.Then, gently insert a 20 gauge needle four to five millimeters into the trachea without any counter-force.The end of the needle should be visible through the trachea.Fill a syringe with 400 microliters of 37 degrees Celsius 2%low melting temperature agarose, and then stabilize the needle with forceps.Keeping the dissection board vertical, slowly instill the entire quantity of warm agarose through the needle into the lungs.Once the lungs are inflated, detach the syringe while keeping the needle inside the trachea and pour approximately 50 milliliters of 20 degrees Celsius PBS over the lungs to help set the agarose.When the agarose has solidified, remove the needle and use forceps to close the trachea to prevent the leakage of any non-solidified agarose.Now, open the chest further by sternotomy and grasp the trachea with forceps.Then, using a pair of surgical scissors, cut through the trachea completely.To remove the lungs, gently pull the trachea up, cut away the connective tissue and esophagus, and pull the lungs completely out of the chest cavity.Immerse the tissue in 37 degrees Celsius RPMI 1640 to wash off the excessive blood.Using scissors and forceps, cut the lobes

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Research

JoVE Journal

Medicine

Ex Vivo Infection of Live Tissue with Oncolytic Viruses

Oncolytic Viruses (OVs) are novel therapeutics that selectively replicate in and kill tumor cells1. Several clinical trials evaluating the effectiveness of a variety of oncolytic platforms including HSV, Reovirus, and Vaccinia OVs as treatment for cancer are currently underway2-5. One key characteristic of oncolytic viruses is that they can be genetically modified to express reporter transgenes which makes it possible to visualize the infection of tissues by microscopy or bio-luminescence imaging6,7. This offers a unique advantage since it is possible to infect tissues from patients ex vivo prior to therapy in order to ascertain the likelihood of successful oncolytic virotherapy8. To this end, it is critical to appropriately sample tissue to compensate for tissue heterogeneity and assess tissue viability, particularly prior to infection9. It is also important to follow viral replication using reporter transgenes if expressed by the oncolytic platform as well as by direct titration of tissues following homogenization in order to discriminate between abortive and productive infection. The object of this protocol is to address these issues and herein describes 1. The sampling and preparation of tumor tissue for cell culture 2. The assessment of tissue viability using the metabolic dye alamar blue 3. Ex vivo infection of cultured tissues with vaccinia virus expressing either GFP or firefly luciferase 4. Detection of transgene expression by fluorescence microscopy or using an In Vivo Imaging System (IVIS) 5. Quantification of virus by plaque assay. This comprehensive method presents several advantages including ease of tissue processing, compensation for tissue heterogeneity, control of tissue viability, and discrimination between abortive infection and bone fide viral replication.

Ex Vivo Infection of Live Tissue with Oncolytic Viruses

Oncolytic viruses are promising for cancer therapeutics. The ability to ascertain the infectability of live tissue specimens obtained from patients prior to treatment is a unique advantage of this therapeutic approach. This protocol describes how to process tissues for ex vivo infection with oncolytic virus and subsequent viral quantification.

Oncolytic Viruses (OVs) are novel therapeutics that selectively replicate in and kill tumor cells1. Several clinical trials evaluating the effectiveness ...

MAME Models for 4D Live-cell Imaging of Tumor: Microenvironment Interactions that Impact Malignant Progression

We have developed 3D coculture models, which we term MAME (mammary architecture and microenvironment engineering), and used them for live-cell imaging in real-time of cell:cell interactions. Our overall goal was to develop models that recapitulate the architecture of preinvasive breast lesions to study their progression to an invasive phenotype. Specifically, we developed models to analyze interactions among pre-malignant breast epithelial cell variants and other cell types of the tumor microenvironment that have been implicated in enhancing or reducing the progression of preinvasive breast epithelial cells to invasive ductal carcinomas. Other cell types studied to date are myoepithelial cells, fibroblasts, macrophages and blood and lymphatic microvascular endothelial cells. In addition to the MAME models, which are designed to recapitulate the cellular interactions within the breast during cancer progression, we have developed comparable models for the progression of prostate cancers. 
Here we illustrate the procedures for establishing the 3D cocultures along with the use of live-cell imaging and a functional proteolysis assay to follow the transition of cocultures of breast ductal carcinoma in situ (DCIS) cells and fibroblasts to an invasive phenotype over time, in this case over twenty-three days in culture. The MAME cocultures consist of multiple layers. Fibroblasts are embedded in the bottom layer of type I collagen. On that is placed a layer of reconstituted basement membrane (rBM) on which DCIS cells are seeded. A final top layer of 2% rBM is included and replenished with every change of media. To image proteolysis associated with the progression to an invasive phenotype, we use dye-quenched (DQ) fluorescent matrix proteins (DQ-collagen I mixed with the layer of collagen I and DQ-collagen IV mixed with the middle layer of rBM) and observe live cultures using confocal microscopy. Optical sections are captured, processed and reconstructed in 3D with Volocity visualization software. Over the course of 23 days in MAME cocultures, the DCIS cells proliferate and coalesce into large invasive structures. Fibroblasts migrate and become incorporated into these invasive structures. Fluorescent proteolytic fragments of the collagens are found in association with the surface of DCIS structures, intracellularly, and also dispersed throughout the surrounding matrix. Drugs that target proteolytic, chemokine/cytokine and kinase pathways or modifications in the cellular composition of the cocultures can reduce the invasiveness, suggesting that MAME models can be used as preclinical screens for novel therapeutic approaches.

We have developed 3D coculture models for live-cell imaging in real-time of interactions among breast tumor cells and other cells in their microenvironment that impact progression to an invasive phenotype. These models can serve as preclinical screens for drugs to target paracrine-induced proteolytic, chemokine/cytokine and kinase pathways implicated in invasiveness.

We have developed 3D coculture models, which we term MAME (mammary architecture and microenvironment engineering), and used them for live-cell imaging in ...

Live Imaging of Drug Responses in the Tumor Microenvironment in Mouse Models of Breast Cancer

The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional co-culture systems are frequently used to explicate tumor-stroma interactions, including their role in drug responses. However, many of the interactions that occur in vivo in the intact microenvironment cannot be completely replicated in these in vitro settings. Thus, direct visualization of these processes in real-time has become an important tool in understanding tumor responses to therapies and identifying the interactions between cancer cells and the stroma that can influence these responses. Here we provide a method for using spinning disk confocal microscopy of live, anesthetized mice to directly observe drug distribution, cancer cell responses and changes in tumor-stroma interactions following administration of systemic therapy in breast cancer models. We describe procedures for labeling different tumor components, treatment of animals for observing therapeutic responses, and the surgical procedure for exposing tumor tissues for imaging up to 40 hours. The results obtained from this protocol are time-lapse movies, in which such processes as drug infiltration, cancer cell death and stromal cell migration can be evaluated using image analysis software.

We describe a method for imaging response to anti-cancer treatment in vivo and at single cell resolution.

The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional ...

Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and Ex vivo Fibroblasts

Invading colorectal cancer (CRC) cells have acquired the capacity to break free from their sister cells, infiltrate the stroma, and remodel the extracellular matrix (ECM). Characterizing the biology of this phenotypically distinct group of cells could substantially improve our understanding of early events during the metastatic cascade.

Tumor invasion is a dynamic process facilitated by bidirectional interactions between malignant epithelium and the cancer associated stroma. In order to examine cell-specific responses at the tumor stroma-interface we have combined organotypic co-culture and laser micro-dissection techniques.
Organotypic models, in which key stromal constituents such as fibroblasts are 3-dimentioanally co-cultured with cancer epithelial cells, are highly manipulatable experimental tools which enable invasion and cancer-stroma interactions to be studied in near-physiological conditions.

Laser microdissection (LMD) is a technique which entails the surgical dissection and extraction of the various strata within tumor tissue, with micron level precision.
By combining these techniques with genomic, transcriptomic and epigenetic profiling we aim to develop a deeper understanding of the molecular characteristics of invading tumor cells and surrounding stromal tissue, and in doing so potentially reveal novel biomarkers and opportunities for drug development in CRC.&#160;&#160;&#160;

Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and Ex vivo Fibroblasts

Molecular profiling of laser microdissected cells and stroma from synthetic, tissue-engineered colorectal cancer models represents a novel and manipulatable approach to characterize and dissect the distinctive biology at the interface between tumor cells at the invasive front and cancer associated stromal cells. &#160;

Invading colorectal cancer (CRC) cells have acquired the capacity to break free from their sister cells, infiltrate the stroma, and remodel the ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

Primary Tumor and MEF Cell Isolation to Study Lung Metastasis

In breast tumorigenesis, the metastatic stage of the disease poses the greatest threat to the affected individual. Normal breast cells with altered genotypes now possess the ability to invade and survive in other tissues. In this protocol, mouse mammary tumors are removed and primary cells are prepared from tumors. The cells isolated from this procedure are then available for gene profiling experiments. For successful metastasis, these cells must be able to intravasate, survive in circulation, extravasate to distant organs, and survive in that new organ system. The lungs are the typical target of breast cancer metastasis. A set of genes have been discovered that mediates the selectivity of metastasis to the lung. Here we describe a method of studying lung metastasis from a genetically engineered mouse model.. Furthermore, another protocol for analyzing mouse embryonic fibroblasts (MEFs) from the mouse embryo is included. MEF cells from the same animal type provide a clue of non-cancer cell gene expression. Together, these techniques are useful in studying mouse mammary tumorigenesis, its associated signaling mechanisms and pathways of the abnormalities in embryos.

The goal of this protocol is to study breast tumorigenesis. With this technique, mouse mammary tumors are removed and primary cells are prepared from tumors. A lung extraction protocol is included for studying lung metastasis. Furthermore, another protocol for analyzing mouse embryonic fibroblasts from the mouse embryo is included.

In breast tumorigenesis, the metastatic stage of the disease poses the greatest threat to the affected individual. Normal breast cells with altered ...

Precision Cut Lung Slices as an Efficient Tool for Ex vivo Pulmonary Vessel Structure and Contractility Studies

The visualization of murine lung tissue provides valuable structural and cellular information regarding the underlying airway and vasculature. However, the preservation of pulmonary vessels that truly represents physiological conditions still presents challenges. In addition, the delicate configuration of murine lungs result in technical challenges preparing samples for high-quality images that preserve both cellular composition and architecture. Similarly, cellular contractility assays can be performed to study the potential of cells to respond to vasoconstrictors in vitro, but these assays do not reproduce the complex environment of the intact lung. In contrast to these technical issues, the precision-cut lung slice (PCLS) method can be applied as an efficient alternative to visualize lung tissue in three dimensions without regional bias and serve as a live surrogate contractility model for up to 10 days. Tissue prepared using PCLS has preserved structure and spatial orientation, making it ideal to study disease processes ex vivo. The location of endogenous tdTomato-labeled cells in PCLS harvested from an inducible tdTomato reporter murine model can be successfully visualized by confocal microscopy. After exposure to vasoconstrictors, PCLS demonstrates the preservation of both vessel contractility and lung structure, which can be captured by a time-lapse module. In combination with the other procedures, such as western blot and RNA analysis, PCLS can contribute to the comprehensive understanding of signaling cascades that underlie a wide variety of disorders and lead to a better understanding of the pathophysiology in pulmonary vascular diseases.

Precision Cut Lung Slices as an Efficient Tool for Ex vivo Pulmonary Vessel Structure and Contractility Studies

Presented here is a protocol for preserving the vascular contractility of PCLS murine lung tissue, resulting in a sophisticated three-dimensional image of the pulmonary vasculature and airway, which can be preserved for up to 10 days that is susceptible to numerous procedures.

The visualization of murine lung tissue provides valuable structural and cellular information regarding the underlying airway and vasculature. However, ...

Organotypic Slice Cultures as Preclinical Models of Tumor Microenvironment in Primary Pancreatic Cancer and Metastasis

Realistic preclinical models of primary pancreatic cancer and metastasis are urgently needed to test the therapy response ex vivo and facilitate personalized patient treatment. However, the absence of tumor-specific microenvironment in currently used models, e.g., patient-derived cell lines and xenografts, only allows limited predictive insights. Organotypic slice cultures (OTSCs) comprise intact multicellular tissue, which can be rapidly used for the spatially resolved drug response testing.
This protocol describes the generation and cultivation of viable tumor slices of pancreatic cancer and its metastasis. Briefly, tissue is casted in low melt agarose and stored in cold isotonic buffer. Next, tissue slices of 300 &#181;m thickness are generated with a vibratome. After preparation, slices are cultured at an air-liquid interface using cell culture inserts and an appropriate cultivation medium. During cultivation, changes in cell differentiation and viability can be monitored. Additionally, this technique enables the application of treatment to viable human tumor tissue ex vivo and subsequent downstream analyses, such as transcriptome and proteome profiling.
OTSCs provide a unique opportunity to test the individual treatment response ex vivo and identify individual transcriptomic and proteomic profiles associated with the respective response of distinct slices of a tumor. OTSCs can be further explored to identify therapeutic strategies to personalize treatment of primary pancreatic cancer and metastasis.

This protocol describes the preparation of organotypic slice cultures (OTSCs). This technique facilitates the ex vivo cultivation of intact multicellular tissue. OTSCs can be used immediately to test for their respective response to drugs in a multicellular environment.

Realistic preclinical models of primary pancreatic cancer and metastasis are urgently needed to test the therapy response ex vivo and facilitate ...

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism

Lung transplantation (LTx) remains the standard of care for end-stage lung disease. A shortage of suitable donor organs and concerns over donor organ quality exacerbated by excessive geographic transportation distance and stringent donor organ acceptance criteria pose limitations to current LTx efforts. Ex situ lung perfusion (ESLP) is an innovative technology that has shown promise in attenuating these limitations. The physiologic ventilation and perfusion of the lungs outside of the inflammatory milieu of the donor body affords ESLP several advantages over traditional cold static preservation (CSP). There is evidence that negative pressure ventilation (NPV) ESLP is superior to positive pressure ventilation (PPV) ESLP, with PPV inducing more significant ventilator-induced lung injury, pro-inflammatory cytokine production, pulmonary edema, and bullae formation. The NPV advantage is perhaps due to the homogenous distribution of intrathoracic pressure across the entire lung surface. The clinical safety and feasibility of a custom NPV-ESLP device have been demonstrated in a recent clinical trial involving extender criteria donor (ECD) human lungs. Herein, the use of this custom device is described in a juvenile porcine model of normothermic NPV-ESLP over a 12 h duration, paying particular attention to management techniques. Pre-surgical preparation, including ESLP software initialization, priming, and de-airing of the ESLP circuit, and the addition of anti-thrombotic, anti-microbial, and anti-inflammatory agents, is specified. The intraoperative techniques of central line insertion, lung biopsy, exsanguination, blood collection, cardiectomy, and pneumonectomy are described. Furthermore, particular focus is paid to anesthetic considerations, with anesthesia induction, maintenance, and dynamic modifications outlined. The protocol also specifies the custom device's initialization, maintenance, and termination of perfusion and ventilation. Dynamic organ management techniques, including alterations in ventilation and metabolic parameters to optimize organ function, are thoroughly described. Finally, the physiological and metabolic assessment of lung function is characterized and depicted in the representative results.

Normothermic Negative Pressure Ventilation Ex Situ Lung Perfusion: Evaluation of Lung Function and Metabolism

This paper describes a porcine model of negative pressure ventilation ex situ lung perfusion, including procurement, attachment, and management on the custom-made platform. Focus is made on anesthetic and surgical techniques, as well as troubleshooting.

Lung transplantation (LTx) remains the standard of care for end-stage lung disease. A shortage of suitable donor organs and concerns over donor organ ...

Ex Vivo and In Vivo Animal Models for Mechanical and Chemical Injuries of Corneal Epithelium

Corneal injury to the ocular surface, including chemical burn and trauma, may cause severe scarring, symblepharon, corneal limbal stem cells deficiency, and result in a large, persistent corneal epithelial defect. Epithelial defect with the following corneal opacity and peripheral neovascularization result in irreversible visual impairment and hinder future management, especially keratoplasty. Since the animal model can be used as an effective drug development platform, models of corneal injury to the mouse and alkali burn to rabbit corneal epithelium are developed here. New Zealand white rabbit is used in the alkali burn model. Different concentrations of sodium hydroxide can be applied onto the central circular area of the cornea for 30 s under intramuscular and topical anesthesia. After copious isotonic normal saline irrigation, residual loose corneal epithelium was removed with corneal burr deep down to the Bowman's layer within this circular area. Wound healing was documented by fluorescein staining under Cobalt blue light. C57BL/6 mice were used in the traumatic model of murine corneal epithelium. The murine central cornea was marked using a skin punch, 2 mm in diameter, and then debrided by a corneal rust ring remover with a 0.5 mm burr under a stereomicroscope. These models can be prospectively used to validate the therapeutic effect of eye drops or mixed agents such as stem cells, which potentially facilitate corneal epithelial regeneration. By observing corneal opacity, peripheral neovascularization, and conjunctival congestion with stereomicroscope and imaging software, therapeutic effects in these animal models can be monitored.

Ex Vivo and In Vivo Animal Models for Mechanical and Chemical Injuries of Corneal Epithelium

Here, animal models based on mouse and rabbit are developed for mechanical and chemical injury of corneal epithelium to screen new therapeutics and the underlying mechanism.

Corneal injury to the ocular surface, including chemical burn and trauma, may cause severe scarring, symblepharon, corneal limbal stem cells deficiency, ...